Spark plug



Aug. 15, 1950 Filed Jan. 15, 1949 Patented Aug. 15, 1950 UNITED STATESPATENT OFFICE SPARK PLUG Guy r. Wetzel, Park Ridge, 111.

Application January 15, 1949, Serial No. 71,158

1 This invention relates to spark plugs and constitutes an improvementover the invention disclosed in my copending application, Serial No,-22,157, filed April 20, 1948, now abandoned.

The spark plugs of said copending application and of the. presentapplication include certain standard elements such as a grounded shelland insulated ignition electrode and a grounded electrode, together withone or more auxiliary electrodes which are also grounded. n

One of the objects of the present invention is one of the 3 Claims. Cl.123-169) frequency discharge the spark occurs more readily andpropagates faster through the combus tion mixturel Another object oftheinvention-is the provision of grounded electrodes as referred to,arranged in a novel manner so as to give asfree a path as possible tothe ionized gas caused by the high ,frequency discharge in thecombustion mixture, and as a consequence thereof rapid propagation .of

combustion is accomplished; as a corollary to this object, the groundedelectrodesare. arranged so that there is a minimum of shielding of thespark,

in the spark gap with the result that the spark or flame propagatesrapidly through the combustion mixture.

A further object is the provision of groundedi electrodes which are flatwith narrow edges and are so arranged that the narrow edges are disposedadjacent the insulated electrode so that frequency discharge havethespark and the high greater eficiency.

A still further object of the invention the provision of flat groundedelectrodes so arranged as to create a greater turbulence of the combus:tion mixture due to their positioning withtheir flat sides facing in thedirections of normal move- Another object ofthe invention is the provi5O sion of two or more grounded electrodes so ar-F ranged that one ofthem cooperates with the insulated electrode for causing a spark and the0th er groundedelectrode produces a' high frequency ment of currents ofthe mixture.

discharge, and with the further provision that the two groundedelectrodes more or less, alternatelybecome the ignition and-auxiliaryelectrodes respectively. r

A still further object of the invention is th provision of a spark plugfor carrying out the objects referred to above which can be produced byordinary manufacturing methods and without the necessity of extremeaccuracy.

Still another object is the provision of a spark plug by means ofwhich'cleaner firing action is accomplished as well as easier startingof the engine whether hot or cold.

With these and other objects in view, my invention consists in theconstruction, arrangement and combination of the various parts of mydevice whereby the objects contemplated are attained as hereinafter morefully set forth, pointed out in the claimsand illustrated in theaccompanying drawings in which: I

Figure l is an elevational view of the spark plug embodying the presentinvention;

Figure 2 is an enlarged view of thelower part of Figure 1 with-a portionthereof shown in section;

Figure 3 is a bottom view of Figure 2;

Figure 4 is a view taken on line 4-4 of Fig ure 2;

Figure 5 is an enlarged detailed view of the electrodes graphicallyillustrating the actionbetween the electrodes;

showing-a modified form of grounded electrodes.

Referring now in detailto the drawings, the reference numeral l2indicates generally a spark plug which forthe most part isastandardplug.-

" The details of-construction of the main part of grounded'with theframe of the engine.

spark plug includes ancentral ignition electrode. Hi which is insulatedbymeansof an insulator I8,

an automobile.

the'lplug need not be dwelt upon except to point out that 'theplugincludes a. metallic shell [4 adapted to be threaded into a sparkplug opening in an engine. The shell 14 is thereby. electrically- Thefrom the shell I4 and is provided with a terminal 2 0 .for connectionwith the ignition circuit of The gr'ounded electrodes are designatedbythe numerals Z4 and 26; The grounded electrodes 24 and 26 aresubstantially identical with each other and each comprises a fiatrelatively thinstrip of material. The material of the groundedelectrodes is any preferred alloy adapted for the purpose. Theelectrodes 24 and 26 may be connected in any suitable manner to theshell l, the latter having as usual an annular lower end. One way ofsecuring the electrodes 24 and 26 to the shell l4 consists inelectrically welding the electrodes thereto as illustrated in Figure 2.Thus, there is an electrically grounded connection between; theelectrodes and. the shell. It will be understood that other means may beemployed for securing the electrodes 24 and '26.

The grounded electrodes 24 and 26 are then bent toward each other asillustrated in the van ous figures. The discharge ends of theelectrodesare then twisted so that the fiat sides thereof are disposed verticallyor in, planes extending longitudinally of the insulated electrode [6.The spark plug will at times be referred to as having a lower end, butit will be understood that this expression refers to vertical:positioning of the plug, and. is. to be interpreted according totherel'ativeposition in which the spark plug will be inserted in theengine.

"The numeral '26 indicates the discharge ends of' the groundedelectrodes 24 and 2G. The discharge ends are disposed adjacent eachother forming a gap 3'0 therebetween. As illustrated.

the gap 30 extendslongitudinally of the insulated electrode-and this gapis relatively small or on the order of from .01 to .025; however, I donot wish to "be limited toanyexact size of gap. A comparison of FiguresZ a-rid 3- will show that the discharge ends 280i the groundedelectrodes have a relatively long and-a relatively short trans versedimensionor as stated above they are gen-- erally flat and thin. V Thenarrow edges of the discharge ends, or the edges across the narrowdimension, are disposed adjacent the lower end of the insulatedelectrode 16 forming therewith a gap" as indicated at 32. The gap '32maybe of a dimension similar to the usual sparkgapabout by very slightinaccuracies in the dimen s'ions' of theelectrodesor in the formingprocess. For" all practical purposes and as iiudgedby'the naked eyethere is no. difference between the lengths "of-these two gaps; however,due to the fact, that {articles such as electrodes ade never perfectgthere is a very slight difference in the lengthsfo'f the two gaps andthis difference ,is

usually only minor.

4 Figure shows-the electrode 2.4" closer to the insulated electrode ['6and as a resultthereofa,

spark. gap issetup between'these two electrodes.

The solid lines L34 graphically illustrate ithat a spark "takes placebetween the. electrodes '24 and i6. .Tl edischarge. endof .theelectrode. '26 :is, spaced a greater distance fromthe insulated-electrode, |.6.- and as. a consequence there. is no. spark created (betweenthese. electrodes. The dotted lines '36 illustrate graphically .a. .highfrequency discharge Or corona effect emitted from thegrounded electrode26.

As pointed out in the copending application referred to above, thisphenomenon is not too well known, but it is known that there is someform of discharge. The discharge is invisible to the naked eye in thedark, but I have shown that the effects of the discharge can definitelybe determined.

The spark occurring across the two electrodes 24 .and 16 eventuallycauses. some loss of metal from the electrode 24 due to electricalerosion. This is illustrated by the cut-out portion 38. The

- upper point of the electrode 24 will then eventually be spaced at agreater distance from the There- IB which then become the ignitionelectrodes.

' The. electrode. 24 then becomes the auxiliary electrode. and the highfrequency discharge or corona effect will be emitted from the electrode24 as illustrated in Figure 6.

Figure? illustrates a modified form of grounded electrode. In thisinstance the grounded electrodw are indicated at 40 and 42. The outerends of these electrodes are of round wire which can be inserted by apress fit in holes inthe shell of the spark plug, or electrically weldedthereto. The discharge-ends of theelectrodes are flattened asillustrated at 44, and are bent toward each other as in the previousembodiment. Thus, the discharge ends of the electrodes 3 53 and aresimilar to and arranged in a manner similar to electrodes 2 4 and 26,but formed from diiierent shaped material.

two grounded electrodes are provided and asfar as manufacturing methodsare con-- cerned' they are identical; however, either one of them maybecome an ignition electrode and the "other an auxiliary electrode andtheir relationship will be reversed from time to time.

The high freque ncy discharge enters into the immediate area or thespark gap with the result that the fuel in that area is disturbed anddesirable turbulence is created in the spark zone. a'result'of'this'action, the spark becomes more effective, and combustionof the fuel accordingly becomes more efiicient. The actionmay becompared generally with disturbing the fire and creating a'greaterir'ont to the fire or combustion and enabling it toipropagatefaster.

The arrangement of the electrodes. with their relatively narrow edgesdisposed adjacent the insulated electrode it and theirfiat, sidesextending longitudinally thereof, provides as wide a path, as possible,for the propagation of the comhustion caused 'by thespark withamin'imum of shielding. or blanketing. The propagation, of the spark isgenerally'dow nwardly and divergent, and as illustrated ill-Figure 4 itwill .be-seenthat the grdunded electrode 26 presents as-small asurfaceas possibletoward the insulated electrode, .or in other Words as greataspace or ipath as possible isarranged so that. the spark and combustionmay readily propagate through .the combustion chamber. :The arrangement'of' the-grounded electrodes is also such that thecorona eiTect orhightrequency dischargecreates. as turbulent effect. as possible'becauseof theiact that it is permitted t0 emergeysidewise from the immediatearea of the spark as well asrd-i-rectly into the sparkgap. .The; highfrequency-discharge agitates the combustion mixture-to a considerabledistance with the result, that =combustiongpropagates. rapidlytherethrough.

A -f urthc v dv n ageof the. arrangementoi the grounded electrodes 24and 26 resides in the effect they have in creating additional mechanicalturbulence in the combustion mixture. The stroke of the piston anddesign of cylinder head sets up a turbulence or currents in thecombustion chamber, and at the top thereof the combustion mixturenormally travels horizontally more so than vertically. This horizontalmovement results in the currents striking the flat sides of the groundedelectrodes whereby a greater turbulence is set up in the gases of thecombustion mixture. This is particularly true in the case of theelectrode portions 28 of Figure 2 and 44 of Figure '7, although theupper portions of the electrodes 24 and 26 of Figure 2 that are securedto the shell are effective in causing turbulence in the gases travellinghorizontally against their flat sides. The increase in turbulence has anadvantageous effect in the propagation of the spark or flame throughoutthe combustion mixture as referred to above.

It will be understood that the number of the grounded electrodes neednot be limited to two, but may be three Or more in number. In any caseonly one of the grounded electrodes will become an ignition electrodeand form a spark gap with the insulated electrode.

It will be thus evident that I'have produced a novel spark plug whichhas a number of important advantages over conventional plugs among whichare easier starting of cold engines; cleaner firing action whereby theplug will operate efiiciently under conditions which cause conventionalplugs to fail because of fouling; and more effective sparking whichcauses the engine to run better. Because of the clean firing of thespark plug of the present invention it can be used about two numberscolder than conventional plugs.

Spark plugs embodying the present invention have been used inautomobiles run over 10,000 miles with no appreciable deterioration, andthe spark plug keeps much cleaner than conventional spark plugs.

It will be seen from the above that I have produced an effective sparkplug which is simple to manufacture and although having numerousadvantages is sufficiently like the conventional spark plug so that itcan be made at low cost and therefore is a commercially practical sparkplug.

While I have herein shown and described a particular embodiment of myinvention, it will be understood of course that I do not wish to belimited thereto since many modifications may be made, and I thereforecontemplate by the appended claims to cover any such modification orsubstitution of mechanical equivalents as fall within the true spiritand scope of my invention.

I claim:

1. A spark plug comprising a grounded shell, a central ignitionelectrode insulated from said shell, and a plurality of electrodesgrounded to said shell, said grounded electrodes being rigid and fixedwith respect to said shell and to said insulated electrode, thedischarge ends of said grounded electrodes being bent toward each otherinto positions longitudinally beyond said insulated electrode, saiddischarge ends being fiat and having a relatively long and a relativelyshort transverse dimension, said long transverse dimension extendinglongitudinally of said insulated electrode, and said flat sides beingthereby disposed in planes parallel with the longitudinal axis of saidinsulated electrode, said discharge ends forming a gap with saidinsulated electrode longitudinally beyond the latter, said dischargeends forming a relatively narrow gap between themselves in a positionlongitudinally beyond said insulated electrode, said discharge endsbeing close together and thereby forming an effectiveiy continuous flatsurface of substantial transverse dimension for baflling combustionmixture flowing in directions transverse to said planes.

2. A spark plug comprising a grounded shell, a central ignitionelectrode insulated from said shell, and a plurality of electrodesgrounded to said shell, said grounded electrodes being rigid and fixedwith respect to said shell and to said insulated electrode, saidgrounded electrodes being of flat material having a relatively long anda relatively short transverse dimension, the ends of said groundedelectrodes secured to said shell being positioned with their longtransverse dimension disposed generally peripherally of said shell,

the discharge ends of said grounded electrodes being bent toward eachother into positions longitudinally beyond said insulated electrode,said discharge ends being disposed with their long transverse dimensionextending longitudinally of said insulated electrode, the fiat sides ofsaid discharge ends being thereby disposed in planes parallel with thelongitudinal axis of said insulated electrode, said discharge endsforming a gap with said insulated electrode longitudinally beyond thelatter, said discharge ends forming a relatively narrow gap betweenthemselves in a position longitudinally beyond said insulated electrode,said discharge ends being close together and thereby forming aneffectively continuous fiat surface of substantial transverse dimensionfor baliiing combustion mixture flowing in directions transverse to saidplanes.

A spark plug comprising a grounded shell, a central ignition electrodeinsulated from said shell, and a plurality of electrodes grounded tosaid shell, said grounded electrodes being rigid and fixed with respectto said shell and to said insulated electrode, the ends of said groundedelectrodes secured to said shell being of substantially round stock, thedischarge ends of said grounded electrodes being bent toward each otherinto positions longitudinally beyond said insulated electrode, saiddischarge ends being fiat and having a relatively long and a relativelyshort transverse dimension, said long transverse dimension extendmglongitudinally of said insulated electrode, and said fiat sides beingthereby disposed in planes parallel with the longitudinal axis of saidinsulated electrode, said discharge ends forming a gap with saidinsulated electrode longitudinaliy beyond the latter, said dischargeends forming a relatively narrow gap between themselves in a positionlongitudinally beyond said insulated electrode, said discharge endsbeing close together and thereby forming an efiectively continuous flatsurface of substantial transverse dimension for baiiiing combustionmixture flowing in directions transverse to said planes.

GUY F. WETZEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,267,597 Schultz May 28, 19181,530,549 Flynt Mar. 24, 1925 1,538,870 Champion May 19, 1925 1,548,556Schmidt Aug. 4, 1925 1,959,639 Pall-lson May 22, 1934

